1. Field of the Invention
This invention relates to a propellantless foam dispenser comprising a container which has a flexible outer wall and contains a foamable liquid and air, such as for instance, a hand-squeezable bottle. The container comprises a base, which is preferably adapted to be placed on a support, and an outlet opening which is disposed at the top of the container and has a foam discharge nozzle associated with it. The dispenser also comprises a foam generator which comprises a body which is fitted in the discharge opening, and when the container is in an inverted position so that the foam generator is disposed below the liquid level in the container, the foam generator is adapted to discharge foam from the container as the latter is squeezed. The body of the foam generator comprises a shell member that is fitted in the outlet opening and a bottom member that is connected to the shell member and contains a porous element, which covers the inlet opening of the foam discharge nozzle. The bottom member is formed with liquid passage openings and with an air passage opening, and a tubular air line is provided which communicates with the air passage opening and extends into the interior of the container close to the base of the container.
2. Discussion of Related Art
A foam dispenser of the afore-mentioned kind is known from FIGS. 3 to 5 of U.S. Pat. No. 3,422,993 and is adapted to dispense, e.g., detergents, polishes and cosmetic preparations in the form of foams. In said foam dispenser the porous element of the foam generator consists of a sponge, which entirely fills the body of the foam generator. As the container is squeezed by hand when it is in an inverted position for use wherein the tubular air line extends into the air space in the container, liquid is forced through the liquid passage openings of the body of the foam generator, and air is simultaneously forced through the tubular air line and the air passage opening so that said liquid and air will enter the sponge and will be mixed in said sponge to form a foam which will then be discharged from the dispenser through the foam discharge nozzle. When the container is subsequently relieved from pressure and returns to its original shape, the container will inhale air which enters from the outside through the foam discharge nozzle and must pass through the sponge before it can enter the interior of the container through the air passage opening of the foam generator and the air line. Because the air must pass through the sponge, the air will be inhaled very slowly so that the user of the foam dispenser must wait for a rather long time before additional foam can be dispensed. Another disadvantage of the known foam dispenser is the fact that the air which during its inhalation passes through the sponge will mix with residual liquid in said sponge so that the air space in the container will soon be filled with foam and a satisfactory discharge of foam will no longer be ensured. That result will be promoted by the fact that the liquid passage openings in the foam generator have a relatively large flow area so that part of the air being inhaled will pass through said liquid passage openings and through the column of liquid that is contained in the container. This will result in the generation of additional foam in the container.